Enhancing the protective performance of organic coatings for marine applications with nepheline-epoxy resin composites

Purpose The marine environment presents a great challenge to the anticorrosion properties of organic coatings applied on equipment. Since the compactness of coatings is critical in marine environments, a novel nepheline-epoxy resin (N-EP) composite was introduced into organic coatings to improve the interfacial compatibility between the pigments and the binder. The purpose of this study is to evaluate the effectiveness of the N-EP composite in enhancing the corrosion resistance of the coatings in marine conditions. Design/methodology/approach These composite particles were prepared via the mechanical ball milling method at thermofield-assisted, leading to chemical bonding between inorganic nepheline and epoxy resin, the agglomeration of particles was avoided by this method. Fourier transform infrared spectroscopy, transmission electron microscope, particle size distribution, sedimentation and thermogravimetric-differential thermal analysis were used to verify the feasibility of thermal field-assisted mechanochemistry for achieving a direct reaction between epoxy resin and nepheline powder, as well as to determine the optimal reaction conditions. Additionally, water absorption tests, Electrochemical impedance spectroscopy and scanning electron microscope were conducted to assess the anticorrosive properties of the modified nepheline coatings. Findings The results further indicated that N-EP improved the barrier performance and mechanical properties of the coating. For example, after modified, the tensile strength of coating had increased from 41.96 ± 0.05–63.14 ± 0.05 MPa. This can be attributed to the less defective N-EP/binder interface and the uniform dispersion of N-EP in the coating. The optimal preparation conditions (500 r/min of ball grinding speed and 6 h of ball grinding time) for the composites were also studied for a superior corrosion resistance of the coating. Originality/value Thermofield-assisted mechanochemistry enables direct reactions between epoxy resin and nepheline powder, enhancing the dispersion stability and interfacial compatibility of N-EP. This modification improves coating compactness, reduces porosity and enhances corrosion resistance by strengthening the labyrinth effect on water diffusion.